Method and apparatus for bending sheet material



Feb. 24, 1948. v, DETTMAN 2,436,383

METHOD AND APPARATUS FOR BENDING SHEET MATERIAL Filed May 27, 1946 2 Sheets-Sheet l 'INVENTOR. Hmaozp V DETTMAN BY M Jum/rfllmvd A r 1 oz ms rs Feb 1943- H. v. DETTMAN 2,436,383

METHOD AND APPARATUS FOR BENDING SHEET MATERIAL Filed May 27; 1946 2 Sheets-Sheet 2 ilfllflllllllllllllllilllllllllllilllllllilll! l4.)

I INVENTOR; Hana/.0 I/DETTMAN fl d am ATTOENEYJ' Patented Feb. 24, 1943 METHOD AND APPARATUS FOR BENDING SHEET MATERIAL Harold V. Dettman, Chicago, Ill. Application May 2'7, 1946, Serial No. 672,366

2 Claims.

This invention relates to a method and apparatus for bending sheet metal to form a seam or fold therein and particularly relates to a method and machine for forming a fold which is known in the trade as a Pittsburgh look.

It is an object of this invention to provide an improved sequence of steps in the making of the fold which is more economical and results in a better fold or Pittsburgh lock.

It is a further object of my invention to provide an improved machine for operating the forming rolls in which there is no tilting action in the frame holding the rolls when a sheet of metal is inserted between the forming rolls. By

my construction the shaft about which the 0D- posing forming rolls rotate are always maintained in parallel alignment which eliminates the pinching of the metal sheet during forming as comm-only occurs in machines of this general character now on the market.

It is also an object of this invention to provide a novel arrangement of the driving gears which operate the forming rolls in the support or frame.

Other objects, advantages and uses of my method and machine will become more apparent by referring to the drawings in which Figure 1 is a side elevation of the machine with a portion cut away in order to illustrate the gearing mechanism.

Figure 2 is a plane view of my apparatus.

Figure 3 is a perspective View partially in section of the end view of my machine which is shown in Figure 4.

Figure 4 is the end view of the machine along the lines 44 of Figure 1.

Figures 5, 6, '7, 8 and 9 illustrate the forming rolls in the sequence of steps used for forming a fold from sheet metal and these forming rolls are also shown in Figure 2.

Referring to the drawings, a frame In is provided having a pair of central plate sections II and i2 to which are bolted by means of bolts l3 outer upper plates I l and i and lower outer plates 16 and IT. The first pair of opposing forming rolls l8 and I9 are keyed to shafts 29 and 30 respectively. The shafts 31 and 38 are journalled in the outer plates M and iii. In a similar manner .the remaining pairs of forming rolls are arranged as follows: rolls 2! and 22 are keyed to shafts 3| and 32 respectively, rolls 22 and 23 are keyed to shafts 33 and 34 respectively, rolls 24 and 25 are keyed to shafts 35 and 36 respectively, rolls 25 and 2! are keyed to shafts 3'1 and 38 respectively, all of said shafts being journalled in the outer plates l4 and I6.

On the opposite side of frame ID from the forming rolls shown in Figures 5 to 9 inclusive, are provided additional forming rolls 2B which may be of the same design and character as those shown in Figures 5 to 9, or may be a diiferent shape and character in order to form bending operations different than those which are made by the forming rolls shown in Figures 5 to 9.

Opposing gears 39 are keyed to each of the shafts 29 to 38 inclusive. Idler gears 40 are provided which mesh with the lower gears 39 as shown. This train of gears are driven as follows:

. A pulley H keyed to shaft 43 is provided and by means of the pulley belt 42 attached to a suitable motor or other means, the driving power is furnished for my apparatus. The chain of gears between the pulley i! and gears 39 are best shown in Figures 3 and 4. A small pinion gear 44 is keyed to the shaft is on the opposite end from the pulley wheel 4!, The gear 44 meshes with the larger gear 45 which is keyed to the shaft 26 and on the end of the shaft 45 opposite the gear 45 is provided another small pinion gear ll. The gear 41 meshes with the gear 48 which is keyed to the shaft 49. The large gear 48 and the small gear 59 in between the plates 5| and -52 are both keyed to the common shaft ifl. The small pinion gear 5%! meshes with the large idler gear 53 which meshes with the pair of the gears 39 which are keyed to the shafts 32 and 34. Thus gears 44, 45, All, 43, 5t! and 53 provide a speed reducing unit which in effect steps up the power required for driving the forming rolls. These latter gears are all in the gear box 54 which is bolted onto the lower pair of plates 16 and I! by means of the bolts l3 as shown in Figure 4. The bolt holes 55 for the bolts it are best shown in Figure 3.

Referring particularly to Figures 2 and 4, the bolts bolt the side plates l4 and I5 and also the side plates l6 and IT.

The preventing of tilting of the shafts on which the opposing forming rolls are attached is accomplished in the following manner. The side plates I l and I5 are bolted to a pair of top plates 56, one at each end of the frame It], by means of the bolts 13. The top plates 56 are also bolted to the central plate II by means of the bolts 51. A leather washer 58 is provided which provides sufficient resiliency that when the metal from which a bend or fold is to be made is inserted between the forming rolls l8 and [9 for example, that only an upward thrust by the shafts 29 occurs and the plates l4 and I5 raise somewhat, permitting the metal to pass through the form- 3 ing rolls l8 and I 9 while still maintaining the shafts 29 and 30 as well as the other shafts to which the forming rolls are keyed in parallel alignment. The bolt 51 also provides a means for taking care of variations in the thickness of the material to be bent or folded.

It should be noted that the upper plates l4 and i are not tightly drawn against the central plate I but are free to move in a vertical direction in order to permit the shafts to which the forming rolls are attached to stay in parallel alignment.

The lower plates 16 and i? are firmly drawn' up against the central plate ll by means of bolts .59. Referring to Figure 4, a portion of thetable x top 60 is shown which provides the support for' guiding the sheet of metal betweenthe forming;

rolls. It is also shown in Figure 1.

The Pittsburgh lock is shown formed in Fig ure 9. The forming of the Pittsburgh :locki by;

my device, is accomplished in the following manner. Referring tov Figures 5 to 9 inclusive, a sheet of metalM is guided .through .the first pair of forming rolls l8 and-i9. Itishould. be noted that the section 5| of the forming roll l8 assisted by the corresponding portion of the lower roll I9 is curved inwardlyand upwardly at an angle. of about 45 which bends the metal M upwardly in a gradualeurve equivalent to an angle. of about 45. This gradual curve is shown'bythenumeral 62; Simultaneously section 63 and sectionxfi l of. roll I8 together with the corresponding opposing sections 64 and B5 of roll 19 form a V 63in the metal adjacent the curved portion .62. The purpose of forming the gradual curve 62 in the first stepof the operation is to remove some of the stretch in the metalwhich is encountered either in the forming operation occurring in the. first roll or in subsequent forming. operations when the offset 68 (shown in Fig. 6) isformed as hereinafter described. It is not desirable to form the offset 68 in the'firstoperation. If the offset is formed in the first operation and a V-bend formed simultaneously, it tends to buckle the metal and stretch it along .the edge of the sheet. If no provision is made in the first forming operation to take care of the. stretching of the metal when the ofisetts is formed, buckling may occurand frequently such a procedure in the forming. of the offset stretches the metal to the point that it tears-in one of. the folds. the rounded upward curve 62 in the first operation, I have insured a uniform forming of the offset by the second pair of rolls without endangering the .te'aring'of the. metal sheet and also the offset is formed in each operation at a uniform height.

Furthermore vI have found that an edge of a sheet of metal when curved upwardflto about an angle. of 45, asisthe curve 63 with a sharp vbend adjacent thereto, .that the upward curve 62 together with the V-bend 63 will act as a guide in guiding the metal through subsequent forming operation in a much straighter lin'e which insures the formation of a uniform fold and also insures that all the Pittsburghlocks so formed by my.

device are uniform in size and shape. Flu'thermore the upward curve 62 and the V t3 eliminates the tendency forthe sheet to crawl or run out from the. rolls. during the formation, operations and results in the. formation .of a much truer-fold.-

greater: than 45. but -.less'than-90' Furthermore Therefore by providing the opposing sections 69 and 1B of the rolls 20 and 2| respectively deepen the V-section 65 and in addition the opposing sections 66 and 61 of the rolls flatten out the portion adjacent the offset 68 into a relative fiat section H in between oifset 68 and deepened V-section 65. In this second step the curvature is taken out of the bend and in its place is formed an oifset and at the sametime theV-section-BE is deepened.

The formation of the offset is made by these rolls without any buckling or turning of the metal because of the formation of the curved section 62 inthe firstset of forming rolls. The formation of theoffsetmade in the second step in passing through the forming rolls 2!) and 2! tends to force the: sheet being folded against the usual guide provided (but not shown) and eliminates all possibilities of the sheet running out of the rolls during the formation of the bend.

In a third set of rolls shown in Figure 7, the offset, 58 is maintained as well as a flat section 7i. Furthermore the v section of the Figure 6 is further deepened by the opposing sections .12 and 13 of the rolls 22 and 23 respectively and at the same time a right angle section 14' is formed adjacent the fiat section H. Sections 35 and 16 of the rolls Hand 23 respectively merely are filler sections to line up the rolls 22 and 23 with the other forming rolls and have no function in the formation of the bend in the metal.

The same is true of filler sections and 16 of rolls .24 and 25 respectively and sections Tl and 78 of rolls 26 and 27 respectively.

In.the third step of the operation one leg of the V 65 is now' in a vertical position and the. other leg isat an angle of approximately 30from the vertical end of the V and is now in position to be folded in under the offset which is accomplished in the forming rolls 24 and 25 as shown inFi'gure 8. The opposing sections 79 and 80 of the rolls 24 and 25 respectively compress the V section 65 and fold it back under the flat section 'H' at an angle of. about 745 relative to the fiat section "II;

The fourth'set. of formingrolls 24 and 25 begins the folding under process and closesthe V 65 so that the two legs of the V bend are flat and parallel to each other.

The fifth set of forming rolls 26 and 27 complete the operation. In this step the V-bend 65 I is flattened andboth sides of .the Vare now parallel 'withthe horizontal section II and the section '14 urged tightly againsteach other and v theleg 15 is spaced from14 in the manner shown in Figure 2 thereby providing the Pittsburgh look]? In this lastv operation'the V-bend B5 is flattened intoplace inside the offset thereby com- Dieting the. lock.

and at-anangle of'about 45 with said metal and simultaneously forming a V bend adjacentto said curve;secondly forming an offset from said curve int'said metal, .said offset being less than but more :than 45. while simultaneously forming a flat section adjacent the ofiset parallel .to but in a difierentaplane than the main body of the metal and'si-multaneou'sly deepening the V bend formed in the first step-and thereafter completing the joint by foldingthe .V bend underneath said flat sectionsiintoiparallel alignment with the -main body oilthe metal andfsaid-fiat portion, the olfset formed in the second step being maintained throughout the subsequent operations.

2. In a sheet metal forming machine for producing a sheet metal joint commonly called a Pittsburghlock, an initially contacted pairof forming rolls for producing in said metal a slow bending curve bending inwardly toward said metal at an angle of about 45 with said metal while simultaneously producing a V-bend adjacent to said curve, a second pair of forming rolls for producing an offset from said curve in said metal, said offset being produced at an angle less than 90 but more than 45 While simultaneously producing a fiat section adjacent the offset parallel to but in a different plane than the main body of said metal, While simultaneously deepening the V-bend formed in the first step and a. plurality of subsequent forming rolls providing means for thereafter completing the joint by folding the V-bend underneath said flat 6 section into parallel alignment with the main body of the metal and said flat section, the said offset formed in the second step being maintained by the subsequent forming rolls throughous the subsequent forming operations.

HAROLD V. DETTMAN.

REFERENCES QETED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,091,381 Neuman Mar. 24, 1914 2,105,240 Flager Jan. 11, 1938 726,691 Johnson Apr. 28, 1903 1,261,735 I-Iunker Apr. 2, 1918 2,283,258 Jensen May 19, 1942 1,347,190 Thomas July 20, 1920 2,275,629 Ingels Mar. 10, 1942 

